The present invention relates in general to ink or printing fluid input systems for use in a rotary printing press and, in particular, to an ink or printing fluid input system in which different ink colors are applied to a single metering roller.
In normal printing practice a single rotary plate cylinder is intended to print only a single ink color. For certain printing operations it is often desired to apply ink in two or more different colors to a single metering roller at different areas along the axial length of the metering roller. For that purpose, two or more ink or printing fluid input devices must be associated with the metering roller and must be separated from each other so that ink of different colors can be applied to the metering roller in the desired areas and so that smearing or mixing of the different colored inks will be avoided.
It is well known in the prior art to use different types of physical barriers between the ink input devices to insure that the different colored inks are kept separated. For example, it is known to use an ink separator plate that extends at right angles to the axis of the metering roller. Such an ink separator plate has a concavely curved end face having the same radius of curvature as that of the metering roller, and is brought into sealing contact with the surface of the metering roller. Also known is the use of sponge type materials in which water is circulated, these sponge type materials contacting the surface of the metering roller at a position for dividing one colored ink from another colored ink.
A drawback of the prior art is that these prior art seals of necessity form mechanical contact with the metering roller. These seals are difficult to set and require constant attention due to wear. Ink containment on anilox rolls used in flexographic and keyless printing press applications are also typically constructed using mechanical type seals which have these same drawbacks.